A varactor is generally a semiconductor device designed to take advantage of variations in its reactance. A varactor may be thought of as a variable voltage capacitor. As a voltage is applied to a varactor, the capacitance of the varactor generally increases. Certain varactors may be used in various types of tuning circuits. As an example, varactors may be useful in certain oscillator circuits, such as oscillator circuits commonly used in communications devices. The operating frequency of an LC oscillator circuit, for example, may be controlled or tuned by varying the voltage across the terminals of a varactor. As another example, varactors may be used in the tuning mechanism of a radio receiver or another device requiring frequency tuning. Two types of varactors include metal oxide semiconductor (MOS) varactors and junction-diode varactors. MOS varactors generally have a higher tuning range than junction-diode varactors, while junction-diode varactors generally exhibit more linear behavior than MOS varactors on their associated capacitance-voltage (C-V) curves.